I have the best FIL. AKA Where to find plans for an ark?

My FIL hates birds, especially poultry, but has a soft spot in his big manly heart for rabbits. So when I asked him for his (years) empty rabbit coop his eyes lit up and he agreed...before asking what I was keeping. LOL. Jumbo coturnix.

I also want 3 silkies...so I showed him some pics of them and how much they are like bunnies...like to be pet, fed, get excited to see you, ect. Now he's agreed to help me build an ark for them!

He's very handy and could probably draw up plans himself...but I feel I present a better case as a responsible poultry owner to bring him blueprints.

Can anyone recommend any free or inexpensive plans for a chicken ark? I don't want anything huge...I'd like a footprint of 4' by 6'. I've searched a bit and found some finished products but am curious enough to ask in my own thread too.

Thanks so much for all the help!
Emily